The selection of pharmaceutically acceptable salts and their crystalline polymorphs is a critical step in the process for researching and developing new medicines. This is because salts or crystalline polymorphs of certain medicines can often be important determinants of ease of preparation of medicine raw materials, solubility, stability during distribution and storage, ease of formulation and pharmacokinetic properties. When the same corresponding composition is crystallized in a different lattice arrangement which results in specific different thermodynamic properties and stabilities, a crystalline polymorph is produced. When two or more crystalline polymorphic substances can be produced, it is preferable to adopt a method of making a pharmaceutically excellent crystalline polymorph into a pure form.
Upon selecting the desired crystalline polymorphism, the properties of many crystalline polymorphs should be compared, and preferred crystalline polymorphisms are selected based on many types of physical properties. One crystalline polymorphic form may be desirable in some circumstances where certain aspects such as ease of manufacture, stability, etc. are deemed important, and in other situations, other crystalline polymorphs may be desirable in terms of greater solubility and/or predominantly pharmacokinetic properties.
In particular, there is a continuing need for drug formulations that exhibit better bioavailability or better stability, and thus continuous research for novel acceptable salts or purer salts of existing medicine molecules and their crystalline forms has been conducted.
Thus, the present inventors have found that a salt of 1-(5-(2,4-difluorophenyl)-1-((3-fluorophenyl)sulfonyl)-4-methoxy-1H-pyrrol-3-yl)-N-methylmethanamine, which is a new active medicinal substance, and a novel crystalline form thereof can be prepared and they can be pharmaceutically used based on their physicochemical properties and stabilities, thereby completing the present invention.